Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 171124
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
424 AM PDT Mon Jun 17 2019

.SYNOPSIS...
There will be a chance of showers and thunderstorms today over
Northeast Washington into the Idaho Panhandle as a weak system
passes through. Warm temperatures will continue into Tuesday. Look
for winds to increase Tuesday and Wednesday with the arrival of a
dry cold front. By Thursday, high temperatures will likely be in
the 60s and low 70s with a chance for showers and thunderstorms. A
cooler and showery pattern is expected to persist through next
weekend.


&&

.DISCUSSION...
Today and tonight: Pattern change underway. A shortwave dropping
down and overtopping the deamplifying positively titled ridge of
high pressure over Eastern Washington and North Idaho has enough
forcing, moisture, and mid-level instability to work with to produce
elevated forced convection, some of it even in the form of
thunderstorms, primarily over the mountain zones over Northeast
Washington and North Idaho. Models suggest it is likely to morph
into surface based convection over the same general locations over
extreme Northeast Washington and North Idaho therefore pops remain
increased into the afternoon and early evening and are mostly in
line with what the operational GFS has been advertising for this
portion of the forecast of late.

Tuesday and Tuesday night: The weak positively tilted ridge
continues deamplification and flattens to a zonal flow with jet
stream positioned within close proximity, if not directly overhead,
of Washington and Idaho. Coupled with the passing of a cold front
this pattern will allow dry and breezy/windy condition which will
heighten converns for spread of any new and existing fires. Some
spotty convection looked possible in earlier model runs but now the
latest runs discount it from happening so there is no mention of
precip. Temperatures show an ever so slight dip but the effects of
the cold front on tempeature are more pronouced when looking ahead
at forecast daytime highs for Wednesday.

Wednesday and Wednesday night: Rather large upper level area of low
pressure sags southward and down from Canada and a significant
portion of it overhangs above Northeast Washington and North Idaho.
The resulting tight pressure gradient produced at the surface by
this change allows for continued robust breezy/windy conditions but
quite cooler conditions. Indeed the cold and conditionally unstable
airmass contained in this upper level feature get placed overhead in
such a manner to possibly result in some weak pulse thunderstorm
activity primarily over the mountains near the British Columbia
border. In addition the low level air is quite dry and combined with
the earlier mentioned breezy/windy/gusty conditions the concern for
spread of any new and existing fires remains. /Pelatti

Thursday: The coldest airmass of the week will settle over the
Pacific Northwest come Thursday as an upper level trough drops 850
mb temperatures to 5 C. As a consequence, chilly morning temperatures
are expected on Thursday with our typical cold valley pockets
possibly dipping into the upper 30s while less sheltered locations
bottom out in the 40s.  One caveat in the forecast is if winds will
weaken enough to allow the atmosphere to decouple. If speeds do
happen to be weaker than currently forecast, expect low temperatures
a bit colder than currently forecast. Afternoon temperatures will
also be rather chilly with highs in the 60s for Spokane and Coeur
d`Alene with 70s down through the Columbia River Valley. By the
afternoon hours on Thursday, expect the cold air aloft to aid in
generating instability showers over the mountains and potentially
down into the lowlands. Given the time of year, thunderstorms will
also be a concern but at this point, they do not look terribly
strong.

Friday-Monday: The upper level trough sticks with us Friday and into
the weekend. This will continue the unsettled weather pattern with
showers and thunderstorms focused over the higher terrain and to a
lesser extent, the lower elevations.  The airmass will also begin
modifying Friday which will bring subtle warming into the weekend.
By late Sunday into Monday, global ensembles suggest a more
organized closed low could move through the Pacific Northwest.  If
this comes to fruition, a better chance of widespread showers will
be possible in addition to some breezy conditions Sunday afternoon
across the Columbia Basin.  Wilson

&&

.AVIATION...

12Z TAFS: A mid level wave over NE Washington tonight will track
into the Idaho Panhandle today producing scattered showers and
thunderstorms. The stronger storms may produce gusty winds, brief
heavy rain, and small hail. A few of these may get close to
KGEG/KSFF/KCOE but the best chances will be in the mountains. VFR
conditions are expected to continue at all TAF sites.


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        85  58  83  53  74  48 /  10   0   0   0   0   0
Coeur d`Alene  83  58  81  53  72  46 /  20  10   0   0   0   0
Pullman        80  56  79  52  71  46 /  10   0   0   0   0   0
Lewiston       88  63  87  58  79  54 /  10   0   0   0   0   0
Colville       87  48  91  44  79  39 /  50  10   0   0   0   0
Sandpoint      81  55  81  52  71  44 /  60  20   0   0  10  10
Kellogg        79  60  77  54  68  49 /  60  20   0   0  10   0
Moses Lake     92  59  89  54  79  49 /   0   0   0   0   0   0
Wenatchee      89  62  84  56  74  51 /   0   0   0   0   0   0
Omak           90  58  87  53  76  48 /  10   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.

&&

$$



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